Battery, battery pack, electronic device, electrically driven vehicle, electric storage device, and electric power system

Abstract

The battery is provided. The battery includes an electrode. The electrode includes a current collector and an active material layer provided on an inside surface of the current collector. The active material layer includes a first region and a second region, where the second region includes an area density lower than the first region, and the second region is provided in a winding-back portion of the active material layer.

The invention claimed is: 
     
       1. A battery comprising an electrode,
 wherein 
 the electrode includes a current collector and an active material layer provided on an inside surface of the current collector, 
 the active material layer includes a first region and a second region, wherein the second region includes an area density lower than the first region, and 
 the second region is provided in a winding-back portion of the active material layer; and 
 wherein the second region includes a recess having a bottom surface. 
 
     
     
       2. The battery according to  claim 1 , wherein a thickness of the active material layer in the second region is thinner than a thickness of the active material layer in the first region. 
     
     
       3. The battery according to  claim 1 , wherein the winding-back portion includes a first winding-back portion of an innermost periphery of the active material layer. 
     
     
       4. The battery according to  claim 1 , wherein the winding-back portion includes a first winding-back portion on a first side of an innermost periphery of the active material layer, and a second winding-back portion on a second side of the innermost periphery of the active material layer. 
     
     
       5. The battery according to  claim 1 , wherein the winding-back portion includes winding-back portions of first and second turns of the active material layer. 
     
     
       6. The battery according to  claim 1 , wherein an area density ratio D 2 /D 1  of an average area density D 2  of the active material layer in the second region to an average area density D 1  of the active material layer in the first region satisfies a relationship of 0<D 2 /D 1 ≤0.9. 
     
     
       7. The battery according to  claim 1 , wherein a width of the second region in a longitudinal direction of the electrode ranges from 1 mm to 20 mm. 
     
     
       8. The battery according to  claim 1 , wherein a width of the second region in a longitudinal direction of the electrode ranges from 5 mm to 20 mm. 
     
     
       9. The battery according to  claim 1 , wherein the electrode includes a positive electrode. 
     
     
       10. The battery according to  claim 9 , wherein
 the current collector includes aluminum or aluminum alloy, and 
 a thickness of the current collector ranges from 8 μm to 15 μm. 
 
     
     
       11. The battery according to  claim 9 , wherein an average area density of the active material layer in the first region is greater than or equal to 12.5 mg/cm 2 . 
     
     
       12. The battery according to  claim 1 , wherein
 the second region includes a recess, and 
 the recess is open while the electrode is wound. 
 
     
     
       13. A battery pack comprising:
 the battery according to  claim 1 ; and 
 a controller configured to control the battery. 
 
     
     
       14. An electronic device comprising the battery according to  claim 1 , wherein power is configured to be supplied from the battery to the electronic device. 
     
     
       15. An electric vehicle comprising:
 the battery according to  claim 1 ; 
 a converter is configured to receive power from the battery to convert the power into driving force of the electric vehicle; and 
 a control device is configured to perform information processing relating to vehicle control based on information about the battery. 
 
     
     
       16. An electric storage device comprising the battery according to  claim 1 , wherein the electric storage device is configured to supply power to an electronic device connected to the battery. 
     
     
       17. An electric power system comprising the battery according to  claim 1 , wherein the electric power system is configured to receive supply of power from the battery. 
     
     
       18. The battery according to  claim 1 , wherein the electrode includes a flat shape electrode configured to be wound from a belt-shaped electrode.